Local Area Network Technology: Part 6

Local Area Network Technology: Part 6 - More Protocols

by Jeff Carrell, Electronic Communications Chairman

In the September issue of Signals, I discussed TCP/IP.

IPX

IPX was designed by Novell and is a derivative of an older networking protocol by XEROX called XNS. IPX has turned into one of the most prominent network protocols, primarily due to the shear volume of Novell NetWare LANs installed the world over. In addition, IBM, Microsoft, LANtastic and other lesser known NOSs have designed their systems so that IPX could be used in addition to their own proprietary protocols.

IPX uses an 8 digit, hexadecimal numbering system, where any numbers between 00000001-FFFFFFFE are valid. Each network segment is assigned a number by the network engineer or system administrator. Each network segment must have a unique number, and no two network segments that are connected in way can have the same number. Occasionally, you’ll find IPX network numbers forming names, such as: da11a5, f005ba11, badf00d and many others.

The IPX address of an individual device is the IPX segment address appended with the NIC MAC address, in the form of: dalla5:0268c14532dc.

Every NIC in a file server that has workstations connected to the same hub, switch or router is a network segment. In the case of a NetWare based file server, even the OS internally has an IPX segment number assigned to it, even though no actual devices communicate on the internal interface. This internal segment address deals with server to server communications.

Although IPX is a very robust and fast performing protocol on a LAN, it does have a bit of a performance issue when traveling over slower speed WAN links, it does slow down and incurs extra overhead. Novell designed an additional protocol called Packet Burst, optimized for use when communicating over WAN links.

NetBIOS

NetBIOS is the primary protocol used by IBM LANs. IBM designed the protocol for their original network operating system, but it was designed in the days of small networks and is not a fast nor extensible protocol. NetBIOS is not routable, therefore if multiple networks need to connect together, there are only a few options. The networks either have to be bridged together, another protocol has to be used by all devices on all networks, or a special form of moving the NetBIOS information must be used - called “tunneling”.

Although still in use by IBM based networks today, more network engineers and managers are opting for more easily deployable protocols like TCP/IP or IPX. One benefit however is that NetBIOS has no numbering or naming convention that has to be configured. All the devices on the network simply use the MAC address of the NICs in order to communicate together.

NetBEUI

NetBEUI was designed by Microsoft and is their primary protocol for their NOSs. NetBEUI is a derivative of NetBIOS and follows the same basic operations and pitfalls. More than anything else, Microsoft wanted the same basic operation of NetBIOS, but needed a few more capabilities that NetBIOS didn’t have. Unfortunately, NetBEUI is also not routable which has presented many network engineers and managers with formidable issues of late. Again, if multiple networks need to connect together, there are only a few options. The networks either have to be bridged together, another protocol has to be used by all devices on all networks, or a special form of moving the NetBEUI information must be used - called “tunneling”.

Tunneling

Some router vendors provide tunneling capabilities for NetBIOS or NetBEUI protocols in their products. The basic function of tunneling is taking the initial NetBEUI or NetBIOS protocol based packet the router port receives, wrapping it an IP packet, providing the “from” and “to” router port addresses in the new IP packet, and then the router sends it on. The receiving router port takes the packet, notices that it has a special signature, decrypts the embedded NetBEUI or NetBIOS packet inside and then sends it on in that native format. Unfortunately, there is some overhead to this function, but if you really need to “route” these two protocols, it is possible.

AppleTalk

Networking capability has been engineered into all Apple Computer products since the very first Macintosh. However, Apple wanted the networking of their computers to be inexpensive compared to other computer and networking products available during those times (1984). Apple engineered a new protocol called AppleTalk.

AppleTalk has three basic numbering components: the network address which uses numbers between 0-65535, the node address using 0-255 and the socket address (used by applications) using 0-255. Additionally, there is the capability of assigning a alphanumeric name to a network address range or group of network address ranges, called the Zone Name.

There have been two major releases of AppleTalk, the original referred to as AppleTalk Phase I, and in 1990 Apple released AppleTalk Phase II. AppleTalk Phase II supported larger networks and more sophisticated AppleTalk routing capabilities. As networking technology advanced, Apple started supporting TCP/IP and IPX on their computers.

Glossary:

AppleTalk Apple network protocol

IP Internet Protocol

IPX Internet Packet eXchange

NetBEUI NetBIOS Extended User Interface

NetBIOS Network Basic Input/Output System

NIC Network Interface Card

NOS Network Operating System

TCP/IP Internet Protocol/Transmission Control Protocol

WAN Wide Area Network

XNS XEROX Network Services (protocol)